LISBON · THE 12-MONTH VERDICT · 38.72° N
The Atlantic runs the calendar here. Lisbon sits on a river mouth that opens west, which gives the city dry, glaring summers and winters that stay green rather than cold: an average high of 79.8°F in August, 56.4°F in January, and no freeze worth packing for in between. Nothing in that range will spoil a trip. What varies, and what decides your dates, is rain and daylight.
That makes Lisbon a rare European capital with no unusable month and one genuinely awkward one. The city is walked, not driven, so the question is whether the cobbles are wet and whether the sun is still up when you finally reach the viewpoint. On July 15 it sets at 9:02 p.m. local time. On December 15 it sets at 5:17 p.m.
THE YEAR AT A GLANCE · LISBON
Go in September: 76.3°F days, 1.14 inches of rain over 2.8 wet days and the ocean near its annual peak at 64.7°F. Take May instead if you’d rather walk the hills than swim.
BEST: SEPTEMBER · WARMEST: AUGUST 79.8°F · WETTEST: NOVEMBER 3.30 IN · QUIETEST: JAN AND FEB
Go for: September and May, when the hills are walkable at 76.3°F and 69.3°F and rain falls on fewer than three days in five weeks.
Think twice before: booking November around the coast or Sintra’s gardens: 7.2 wet days, 3.30 inches and sunset at 5:24 p.m. on the 15th.
Normals: Open-Meteo / ERA5 1991-2020, grid cell rather than a station · Sea: Open-Meteo Marine, mean of daily maxima 2015-2024 · Daylight: sunrise-sunset.org · full sources at the end
On this page
- Lisbon weather month by monthHighs, lows, rain days and sea, all twelve
- The single best month for a first visitSeptember, with the numbers
- Sea temperature month by month58.8°F to 66.8°F, and what that means
- When is Lisbon quietest?Mid-January to the end of February
- Which month is the wettestNovember, 3.30 inches over 7.2 days
- April and May against September and OctoberThe shoulder verdict
- Lisbon in one specific monthThe twelve month guides
The spread is what makes this city plannable. July records 0.09 inches of rain and November 3.30, a difference of more than thirty to one, while the ocean shifts only 8°F across the entire year, from 58.8°F in February to 66.8°F in June. Air temperature is rarely the problem in Lisbon. Rainfall and light are.
Lisbon weather month by month: highs, lows, rain and sea
| Month | Avg high / low (°F) | Precip | Days ≥ 0.10 in | Sea (°F) | Daylight, 15th |
|---|---|---|---|---|---|
| January | 56.4 / 48.3 | 2.70 in | 6.6 | 59.4 | 9h48 |
| February | 57.8 / 48.5 | 2.04 in | 5.3 | 58.8 | 10h48 |
| March | 61.9 / 51.3 | 2.11 in | 5.3 | 59.4 | 12h00 |
| April | 64.4 / 53.9 | 2.09 in | 5.7 | 62.2 | 13h17 |
| May | 69.3 / 57.7 | 1.73 in | 4.2 | 63.1 | 14h21 |
| June | 74.8 / 61.8 | 0.42 in | 1.1 | 66.8 | 14h55 |
| July | 78.6 / 64.3 | 0.09 in | 0.2 | 66.7 | 14h39 |
| August | 79.8 / 65.4 | 0.17 in | 0.5 | 66.2 | 13h43 |
| September | 76.3 / 63.9 | 1.14 in | 2.8 | 64.7 | 12h29 |
| October | 69.9 / 60.1 | 3.06 in | 7.0 | 66.3 | 11h14 |
| November | 62.3 / 54.1 | 3.30 in | 7.2 | 63.7 | 10h07 |
| December | 57.9 / 50.1 | 3.12 in | 7.0 | 60.7 | 9h31 |
The year has one long dry trough with wet edges on either side. Rainfall falls from 2.70 inches in January to 0.09 inches in July, then climbs back to 3.30 inches by November, while the daily high swings 23.4°F between January and August. Winter never turns properly cold: the coldest average low of the year, 48.3°F in January, is a light jacket.
The switch happens quickly, twice. May still logs 4.2 days of measurable rain and June only 1.1, so summer effectively begins in a fortnight. Coming back down, September records 1.14 inches over 2.8 wet days and October 3.06 inches over 7.0, which is the wet season arriving rather than approaching. October is also the month where the numbers argue with each other: the water is still 66.3°F while the sky delivers rain on seven days.
August is the hardest month for the way most people use this city. Lisbon is a stack of stairs and cobbled ramps, and 79.8°F highs with 0.5 wet days of cloud cover mean the climb to the castle is done in full sun. Families tied to school holidays manage it by inverting the day, out at eight, indoors from one. Anyone free to choose their dates has no reason to take that trade.
One caveat about where these numbers come from. The normals are a model reanalysis for the grid cell centered on 38.7223° N, 9.1393° W over 1991 to 2020, not the log of a single airport thermometer, and a wet day in the table means 0.10 inch (2.5 mm) or more. The cell averages river, city and hillside together, so Cascais on the open Atlantic runs breezier and Sintra, 1,000 feet up in its own cloud, runs wetter than anything printed above.
When is the best time to visit Lisbon?
September, and it isn’t close. Average high 76.3°F, average low 63.9°F, 1.14 inches of rain across 2.8 wet days, the sea at 64.7°F and 12 hours 29 minutes of daylight with sunset at 7:45 p.m. on the 15th. You get summer conditions with the terraces still open, the beach trains still running, and the hills climbable before noon.
Against its neighbors the case holds. August is 3.5°F warmer by day and its water 1.5°F warmer, a gain most travelers would not notice, bought at the price of the peak summer crush. October is the closer rival and loses on rain: 3.06 inches over 7.0 wet days against September’s 1.14 inches over 2.8, plus 6.4°F off the daytime high and 75 fewer minutes of daylight.
The week-by-week picture, including how quickly the first week differs from the last, sits in Lisbon in September. If your dates are fixed elsewhere, May and October carry their own detail, and the national view is in the best time to visit Portugal.
When can you swim in Lisbon? Sea temperature month by month
By the roughly 68°F yardstick most American swimmers use, the ocean off Lisbon never quite gets there on a monthly average. Its ceiling is 66.8°F in June, with July at 66.7°F, October at 66.3°F and August at 66.2°F all within seven tenths of it. September drops to 64.7°F and November holds a surprising 63.7°F, warmer than May’s 63.1°F. The floor is February at 58.8°F, with January and March both 59.4°F, which is a wetsuit or a very brief act of bravado.
Read those figures for what they are: the mean of daily maxima over 2015 to 2024, so a shade warmer than a 24-hour average and warmer still than the water at nine in the morning. The Atlantic here also refuses to behave like the Mediterranean, dropping several degrees when the north wind pushes cold water up the coast. Plan the swim for the afternoon, and expect the first thirty seconds to be a negotiation.
When is Lisbon quietest?
The hollow runs from the second week of January to the end of February, between the New Year departures and the Easter break, with a shorter dip in late November before the Christmas lights go up. That is a statement about the calendar, not about prices: Portuguese schools are in session, the beach resorts down the coast are out of season, and the visitors left in the city are the ones who came for the city.
What you gain is access. February is the driest of the cold months at 2.04 inches over 5.3 wet days, fewer wet days than April’s 5.7, and the sun stays up until 6:14 p.m. by the 15th. Tram 28 is a tram again rather than a queue, the miradouros belong to whoever turns up, and 57.8°F is a comfortable temperature for climbing to them. The fado houses are full of people who live here.
What you lose, in order: light, then water, then terraces. January 15 gives 9 hours 48 minutes of daylight, five hours less than June 15, with sunrise at 7:51 a.m. and sunset at 5:39 p.m., which means Belém and one museum is a full day. The sea bottoms out at 58.8°F. January also drops 2.70 inches over 6.6 wet days, and Sintra’s gardens in steady drizzle are a different and gloomier outing.
Which month should you avoid in Lisbon?
November, for anyone whose trip involves the coast, the hilltop gardens or long afternoons outdoors. It is the wettest month of the year at 3.30 inches, spread over 7.2 days at 0.10 inch or more and 0.4 days at a full inch or more, with 10 hours 7 minutes of daylight and sunset at 5:24 p.m. on the 15th. A day trip that depends on a view is a coin flip. City-break travelers with a museum list will barely notice.
The month still has an argument. Its 62.3°F highs beat March’s 61.9°F, the ocean holds 63.7°F, warmer than May, and the streets are as calm as they get before Christmas. Take the wet-weather insurance seriously: the National Tile Museum, the Gulbenkian, a covered market lunch, and Lisbon in November for the day-by-day shape of it.
Is the shoulder season worth it in Lisbon?
Lisbon’s shoulders are April and May on the way up, September and October on the way down. Set against August’s 79.8°F, May runs 10.5°F cooler by day and April 15.4°F cooler, while September gives up only 3.5°F. October arrives at 69.9°F, the same daytime warmth as May, and pays for it with 7.0 wet days against May’s 4.2.
The gain is walkability plus light. May 15 delivers 14 hours 21 minutes of daylight, just 34 minutes short of the June solstice figure, with sunset at 8:43 p.m., and does it at 69.3°F rather than 79.8°F. That combination is what makes Alfama, the Bairro Alto slope and a Sintra day trip possible on the same trip without collapsing at three in the afternoon.
The cost is measurable in rain and in water temperature. May sees 4.2 wet days to July’s 0.2, and April 5.7, more than any month from May through September. April’s sea at 62.2°F is 4.6°F below June’s peak, so the beach at Carcavelos becomes a walk rather than a swim. October’s 3.06 inches is nearly triple September’s 1.14.
So the shoulder earns it, with a division of labor. May is the pick for walking, viewpoints and Sintra. September is the pick if swimming matters at all. April works when daylight outranks water. October is worth booking for the first half of the month and treated as a gamble after the 20th.
The last word
Book September if the dates are yours, May if they are not, and keep November for the museums and the fado cellars. One more marker for anyone building a longer trip: on March 15 the sun is up for exactly twelve hours, setting at 6:45 p.m., yet the ocean is still sitting at its January value of 59.4°F. That gap between the light and the water is Lisbon’s whole spring, and it closes in about six weeks.
Sources & data for this guide
- Monthly highs, lows and precipitation, 1991-2020 · Open-Meteo / ECMWF ERA5, grid cell 38.7223° N, 9.1393° W · model reanalysis, not a single-station record · checked Sep 9, 2026
- Wet-day counts (0.10 inch and 1 inch thresholds) · same ERA5 series, 1991-2020 · checked Sep 9, 2026
- Sea surface temperature · Open-Meteo Marine API, mean of daily maxima 2015-2024 · a shade warmer than a 24-hour mean · checked Sep 9, 2026
- Sunrise, sunset and daylight length on the 15th of each month · sunrise-sunset.org, converted from UTC to Europe/Lisbon · checked Sep 9, 2026
- Season timing (school breaks, the January to February hollow, the pre-Christmas dip) is editorial calendar reading, not a price series: we carry no hotel or airfare data for Lisbon and make no claim about which month is cheapest.
- The roughly 68°F swimming comfort threshold is our editorial yardstick, not a published standard.